class Animals:
    def breathe(self):
        print ("breathing")
    def move(self):
        print ("moving")
    def eat(self):
        print ("eating food")

class Mammals(Animals):
    def breastfeed(self):
        print ("feeding young")

class Cats(Mammals):
    def __init__(self,spots):  # 用于给实例化对象赋初值
        self.spots = spots
    def catch_mouse(self):
        print ("catch mouse")

kitty = Cats(10)
print (kitty.spots)
kitty.catch_mouse()
